1. Field
Example embodiments relate to a nano electromechanical system, and for example, to a nano-resonator including a beam with a composite structure.
2. Description of Related Art
A conventional micro electromechanical system (MEMS) includes a sensor for detecting various physical or chemical properties. As a dimension of a mechanical transducer is reduced, a new generation system having improved sensitivity, spatial resolution, energy efficiency, and reaction time, which is referred to as a nano electromechanical system (NEMS), has been developed.
For an apparatus in the communications field, a higher favorability, i.e., a higher Q (quality factor) value, is desired, so that a mechanical device may be used in an electronic device, e.g., in a SAW or a Film Bulk Acoustic Resonator FBAR. In the electronic device, frequency tuning may not operate structurally, and a next generation mechanism having a nano-mechanical resonator is needed.
In the case of a mechanical vibration, a resonant frequency fo may be expressed as
            f      o        =                  1                  2          ⁢          π                    ⁢                                    k            r                                m            r                                ,where kr is a spring constant and mr is mass. The spring constant kr is inversely proportional to a length of a beam and increases in proportion to width and thickness of the beam. The mass mr is a product of a volume and a density (mass/volume) of the beam and is proportional to a magnitude of the entire beam.
In relatively colder temperatures, a trial performance of a conventional nano-resonator of a nano size at a level of giga-hertz (GHz) was performed. However, a conventional nano-resonator has technical problems at room temperature and atmospheric pressure, and in a normal magnetic field, i.e., in non-superconductivity.
In order to solve the technical problems of a conventional nano-resonator and to realize a practical application of the conventional nano-resonator at room temperature and atmospheric pressure, and in a non-superconductive magnetic field, a nano-beam of double or multiple structure has been suggested. If the nano-resonator is used as a communication apparatus (for example, as a filter and oscillator) in a higher frequency region (i.e., gigahertz (GHz) or more), Young's Modulus and stiffness of larger values are required. GaAs, Si and SiC are NEMS materials having values which meet the requirements of Young's Modulus and stiffness of larger values. For example, SiC has a larger value and a stability of SiC is recognized. However, vapor deposition of SiC is more difficult, and a limitation value for SiC is up to 30 nm. Due to the electrical conductivity of SiC, signal detection may be made only in a chamber of liquid He having a relatively lower temperature and a relatively lower pressure. The signal detection may be made only under superconductive magnetic force lines (e.g., up to 8 T).
Accordingly, a conventional nano-resonator has a lower electrical conductivity and requires a chamber having relatively lower temperature, relatively lower pressure, and superconductive magnetic force lines. Therefore, the conventional nano-resonator may not be used at room temperature and atmospheric pressure or in a non-superconductive magnetic field. The conventional nano-resonator is more difficult to operate in the higher-frequency region of giga-hertz (GHz) or more.